1. Field of the Invention
This invention pertains to a winding roller, consisting of a winding tube and two end disks, to wind and unwind photopolymer films.
2. Description of the Related Art
European Patent Application No. 212,203 discloses a winding roller of the kind in which two end disks are slipped onto the protruding ends of the winding tube and pressed onto the end faces of the reel, thus becoming firmly attached. In order to form this attachment, according to the teaching of the above-mentioned application, the end disks are attached to the winding tube by means of clamping springs or of barbs, or else they are glued onto it. These embodiments require either additional parts (clamping springs) or materials (adhesive), or else they call for the winding tube to be provided with appropriate projections to support the barbs.
Another known embodiment is a winding roller which has been used by the applicant since 1977, consisting of a winding tube made of cardboard and two slip-on end disks (1), which have three clamping cams (3) on their inner circumference (2), as shown in FIGS. 1a and 1b. The inner diameter d.sub.1 of the end disk opening and the dimensions of the clamping cams are chosen in such a way that the diameter of the winding tube, including its tolerance, has a value which lies between d.sub.1 and the diameter d.sub.2 of the circle defined by the tips of the clamping cams. When the end disks are slipped on, the winding tube is deformed, partially plastically, partially elastically, by the clamping cams. Consequently, the end disks can only be slid onto the winding tube with a certain amount of force. However, this deformation of the winding tube is not suitable for winding tubes made of hard material such as, for example, polystyrene.
The objective of the innovation is to design the end disks of this type of winding tube in such a way that the disks can be slipped onto a smooth winding tube in the direction of the end face of the film reel without the need to apply any substantial amount of force while, at the same time, preventing sliding in the opposite direction. In addition, the new end disks should not call for any additional parts or material for their attachment.